Heating method and apparatus



1,542,956 F. PUENING HETING METHD AND APPARATUS Filed Jan, 31, 1923 3Sheets-Sheet l Jane 23, 1925.

lJune'23, 1925.

PatentedJune 23, 1925;

FRANZ PUENING, OF ASPINWALL, PENNSYLVANIA.

HEATING METHOD AND APPARATUS.

Application led January 81, 1923. Serial No. 616,138.

To all whom t may concern.'

Be it known that I, FRANZ PUENING, a citizen of the United States, andresident of Aspinwall, in the county of Allegheny and StateoflPennsylvania, have invented a new and useful Improvement in HeatingMethods and Apparatus; and I do hereby declare the following to be afull, clear, and exactf ject or space to be heated, and are givenadditional heat during each reciprocation either by introducing freshgases of combustion into the reciprocating body of gases or by passingthe reciprocating gases in contact with a source of heat.

One object of my invention is to provide ay system of heating by meansof reciprocating gases in which a single source of heat shall bearranged to supply equal amounts of heat to a heating chamberalternately from two sides of said chamber.

-Another object of my invention is to add heat to the reciprocated gasesat each reciprocation while they are moving away from the obj ect orspace to be heated and to thoroughly distribute the new heat in thegases before reciprocating them again through the heating chamber.

In my copending applications for Letters Patent filed July 16, 1920,Serial No..396, 693, December 11, 1922, Serial No. 606,037, and January18, 1923, Serial No. 613,396, I have disclosed several methods ofcarrying out the reciprocating-gas system of heating. In all of theseprior methods two sources of heat were provided, one burner, or set ofburners being located von each side of the body or space to be heated.If the two burners or sets of burners are of exactly equal heatintensity, an equal amount. of heat is transmitted from each side to thespace or object to be heated. In practice it sponding variations in theheat delivered by the reciprocating gases. It has also .to be recognizedthat the investment for two sources of heat is higher than for only one,and that the heat radiation losses from two high-temperature sources ofheat are greater than from only one.

In my priorsystems, where the reciprocating gases are heated at twopoints in their reciprocation, it is of course possible to extinguishone of the burners or sets. of burners and to heat the reciprocatinggases at one point only in their reciprocation. It is evident, however,that insuch a case the heat becomes less intense on the side of theheating chamber where the heat source was extinguished, and that theheat within the heating chamber is no longer uniform.

According to my present invention I prov ide a system of heating bymeans of reciprocating gases, wherein equal amounts of heat are suppliedto the heating chamber alternately from two sides, but with the use ofonly a single source of heat. For this purpose I provide a by-pass tothe heating chamber or the heating flues in such a manner that therecipiocated gases are divided into two streams during eachreciprocation. The dimensions of the by-pass are preferably such thatonly the smaller portion of the' total reciprocating gas volume can passthrough it., While the bulk of the gas passes through the heatingchamber proper. The reciprocation of the gases is produced as in myprior applications by means of a piston member which may be arranged toreciprocate in a strai ht line, to oscillateA about a fixed pivot, or 1nany other manner as may be desired.

The motion of the piston in one direction crea-tes a pressure in thespace toward which it moves and 'a suction in the space from which itmoves away. This pressure and this suction extend in both directions inan ever diminishing intensity until they ,meet at a certain point of theheating chamber and also at a point of the by-pass, where pressure aswell as suction have disappeared v and neutral conditions exist. At thisneu.- tral point in the by-pass the additional heat is introduced andadded to the smaller stream ofgases which reciprocate through theby-pass. 1

This by-pass conducts the gases into the chamber containing the pistonwhich reciprocates the gases through the system, and

the hot-gases from the by-pass are therein heat. In this way the gasesare mixed uniformly before being introduced into the heating chamber.Another important feature of my invention is that heat is not added-to'the recipro-iV j cated gases while they are .on theirnva'y` toward the`body to be heated, :but'fwhilel they are moving away from it intotheauxiliary chamber in which the piston reciprocates. There they arethoroughly mlxed vwith the older gases coming from the body to be heatedwith the result that the temperature of the mixed gases, when they arereturned to the bodies to be heated, is even more uniform than in thesystems shown in my prior applications. This is of importance where thebodies to be heated are very sensitive tov overheating. Other advantagesof myrinvention will appear from the followingdescription, taken .inconnection with the accompanying drawing, wherein Fig. 1-

is a longitudinal vertical sectional .view 'takencentrally through afurnace having an oscillating piston for reciprocating heating gases inthe furnace chamber; Fig. 2 is a transverse` vertical-sectional viewtaken substantially on'the line 2-2, Fig. 1; Fig. 3-

is an enlarged-side view, artly in elevation and partly in section, o a,ortion 'of the oscillating piston shown in igs. l and'2; Fig. 4 is anend elevational view of the piston construction shown in Fig. 3; Fig. 5is an enlarged end elevational view of a portion of the furnaceconstruction of Figs. 1

f and 2; Fig.6 is a horizontal sectional view through va furnaceprovided with a vertically moving iston for reciprocating gases throughthe fiirnace chamber; and Fig. 7 is'a vertical sectional view takensubstantially on the line 7-'7, Fig. 6.

It is to be understood -that my invention is in no way` limited to theheating of any particular object or class of objects, and

that the structures shown in the accompanying drawing are intendedmerely to illustrate some. ofthe many embodiments of which my inventionis capable.

Figs. 1 to -show the principles of my invention as applied to anelongated furnace chamber 2 through which hot gases are reciprocatedtransversely by means, of an oscillating piston 3. The piston 3 isenclosed within a piston chamber 4, the vlower Wall 5 of which iscircularly curved about the axis of'rotation of the piston 3. A- hollowshaft 6 supports and swings the p iston 3 and is mounted upon bearings 7resting upon standards which are located outside of the piston chamber,and which consist of horizontal beams 8 and vertical 'supports 9. lAcrank 10 is shown attached to one endof the hollow shaft 6 and may 11,the upper ends of which extend through the openings in the shaft 6 andhave their upper ends closed by -means of plugs 12.

The lower ends of the pipes 1l are attached to and communicate with ahorizontal pipe v13, and each pipe l1 has near its upper end one or morelateral openings 14 communieating with the interior of the hollow shaft6. The ow of liquid through ythe shaft 6 is controlled by means ofpartitions 15 having restricted openings 16. One end of the shaft 6 is'connected to a-suitable source of water or other cooling luid, and thisfluid traverses the pipes 1l and 13, as well as the shaft 6, thuseffectively cooling the piston.

The panels in the frame which is formed by the shaft 6 and the pipes 11and 13, are covered ywith plates 17 which may be plain rectangular metalsheets or may, with advantage, be corrugated, as shown on the drawing.These plates may be secured in place vby means of bolts 18 which extendthrough the plates near their upper and lower edges, and also extendthrough openings in webs or ribs 19 which are welded or `otherwisesecured to theshaft 6 and to the pipe 13.

The oscillating piston may extend the full length of the furnace or, ina long furnace, may be divided into two or more sections. Fig. 1 showssuch a construction in which the piston consists of two sections ofequal length separated by a vertical wall 2O which also may provide anintermediate bearing for the hollow shaft 6. This vertical wall alsocontrols the fresh hot gases which are introduced into the system in themanner described below, and compels these fresh gases to reci rocatethrough the heating chamber 2 be ore reaching the rear portion of thepiston chamber 4.

In order to prevent Agases from` passing above the 'shaft 6, a sealingmember 21 extends the full length of the piston chamber 4 and restsloosely upon the upper surface of the shaft 6, being held in position bymeans of hooked brackets 22 which are secured to the underside of anarch 23. The sealing member 21, like the piston 3, may be constructed inone or more sections, as may be found convenient.

The piston chamber 4 and the main heat- I vertical lues 24, the lowerends of which open into the piston chamber 4, while their upper endsopen into spaces 25 which extend the full length of the furnace and areseparated from the mainheating chamber 2 by vertical walls 26 havingopenings 27 for the passage of hot gases, the effective size and numberof these openings being made variable, if desired, by means of pieces ofbrick shown at 28.

The piston chamber 4 is separated from the main heating chamber 2 by thearch 23 and by an additional arch 29 which is of sufficient depth tocontain a horizontal flue 30 through which fresh hot gases are added tothe gases which are Ireciprocated at each stroke of the piston 3. Theflue 30 preferably extends beneath only a portion of the length of theheating chamber 2 for reasons which will be discussed below, althoughthis flue may, if desired, be made to extend the full length of theheating chamber 2. At its outer end theflue 30 communicates with afire-box 31 into which projects a burner 32.

In the bottom of the flue 30 and midway between its sides are a row ofopenings 33 that are connected by means of curved bypass channels 34with the vertical flues 24 which are adjacent to the flue 30. In orderto adjust the effective size ofthe openings 33, bricks 35 are providedto .rest on the bottom of the flue 30 and may be adjusted to close theopenings 33 to any desired extent by means of a rake or other suitableimplement inserted through an opening 36 in the front wall of thefire-box 31.v

The furnace and its attachments are so constructedv as to be capable ofbeing taken apart for shipping or storing. For this purpose I dispensewith ordinary'brick or concrete foundations and mount the furnace upon astructural steel foundation frame, including transverse horizontalchannels 37 vertical channels 38, and inclined struts 39 which arebolted at their lower ends to the transverse channels 37 and are securedat their upper ends to the vertical channels 38 by means of gussetplates 39a. As best shown in Fig. 5, longitudinal channel beams 40 aresecured to the upper ends of the vertical channels 38 by means of anglepieces 40a and other longitudinal channelv beams 41 are bolted to theupper flanges of the channel beams 40. The channel beams 4l open towardeach other and are inclined to form skewback seats for the ends of thearch 23 which supports the weight of the furnace walls and roof.Horizontal angles 42 are secured to the channels 37 and 38 for addingrigidity to the framework. A curved metal shell 43 is attached at itsupper edges to the lower flanges of the channels 4l and serves tosupport the curved wall 5 of the piston chamber 4.

As in all my reciprocating-gas systems of heating ,where fresh hot gasesare added to the reciprocated gas body, it is necessary to withdrawwaste gases from the present systemv corresponding in volume to thefresh hot'gases that are added to the system. For this purpose I providean outlet 45 at the rear end of the furnace, this outlet beingpreferably located at the floor of the furnace, and midway between itssides. As shown on Fig. 2 the outlet 45 communicates through a pipe 46with a pipe 47 which, conducts the waste gases to a suitable chimney orwhich may itself act as a chimney.

In the operation of the furnaceshown in Figs. l to 6, the piston 3oscillates within the chamber 4 and at each stroke drives hot gasesahead ofit. The courses followed by these gases are indicated by meansof arrows on Fig. 2, it being assumed that the piston 3 at this momentis moving to the left in Fig. 2. The greater portion of the gases forcedahead of the piston pass up through the flues 24 at the left, enter theheating chamber 2 through the openings 27, and' return to the pistonchamber through the vertical flues 24 at the right. Another and smallerportion of the moving gases enters the by-pass channels 34 and againjoins the main stream of gases in the vertical lues 24 at the right ofFig. 2. Hot gases from the burner 32 are` added to the gases whichtraverse the by-pass channels 34, and these fresh gases are added to themain body of the reciprocating gases while the gases are moving towardthe piston chamber 4. While the space at the right of the piston in Fig.2 is being filled, the fresh hot gases which have been broughtl inthrough the by-pass channels are thoroughly mixed with the older gasesfrom the main heating chamber 2. When the movement of the piston 3 isreversed, the same action takes place in the reverse direction, thegases that are now forced up through the lues 24 at the right of Fig. 2being very uniform intemperature on account of the mixing action justmentioned.

,It is to be noted particularly that the openings 33, through whichfresh hot gases are added to the reciprocating gases, are located at apoint of neutral pressure, that is to say, where there is neitherpresfure which would Ainterfere with the issuance of hot gases throughthe openings 33, nor substantial suction which would draw gases throughthese openings at an unduly high rate. This condition is sho-wnnumerically o-n Fig. 2, it being assumed that the piston 3 is moving tothe: left in this ligure and is developing a pressure of one unit.Immediately in| front of the piston 3 there is a. positive pressure ofl-i-l unit, and immediately behind it there is a negative pressure orsuction of -1 unit. In those parts of the by-pass channels 34, where thegases at this point. This condition of neutral pressure, indica-ted bythe symbol i 0', ex-

ists throughout the stroke of the piston, and when the direction of thepiston is reversed the neutral condition is maintained, although the'pressures and suctions are reversedl in the system. n

Similarly, the outlet 45 through which' waste gases are withdrawn fromthe furnace is'located at a point of neutral pressure indicated b-y :t0, this neutral condition being produced, as in the by-pass channels 34,by the balancing of the positive and `negative pressures produced by thepiston 3.

The portion ofthe heating chamber 2 which is adjacent to the horizontalflue 30 is maintained at a higher temperature than the remainder of theheating chamber, for the reason that the hot gases supplied through thisflue and through the by-pass iu'es 34 must reciprocate several times'through the heating chamber 2 and the piston chamber 4 before reachingthel opposite end of the heating chamber, and receive no additional heatbeyond the end of the flue 30. The temperature flow is also retarded bythe partition 20 in the piston chamber. progressively decreasingtemperature is thus produced in the heating chamber, this conditionbeing desirable when the articles to be heated are moved through theheating chamber from the cooler end to the hotter end, as in a tunnelkiln. A similar arrangement may be employed in heating vertical tanks orthe like, the more intense heat being applied to the upper end oftbe'tank and the cooler waste gases being withdrawn from the lower endof the tank. In such a ,-case, the flues for the gases may be arrangedchamber and the main heating chamber, in'

which case the frcshhot gases may be in- 4troduced into one or bothends. ofthe flue 30 or at one or more intermediate points; or the flue30 may be placed above the heating chamber 2.

The bodfy of hot gases which reciprocatesl in the system of Figs. l and2 may be considered as a stream having its edges at the front and rearof the furnace and flowing transversely to the long axis of the furnace.It will be seen that the fresh hot gases are added to this stre-am at ornear one of its edges and that the waste gases are withdrawn from theflowing stream at or near its opposite edge.

Figs. 6 and 7 of the drawing s how al furnace chamber 52 enclosed bywalls 53 of refractory material and having near its ends vertical walls54 which separate the main furnace chamber 52 from smaller end chambers55. The walls 54 are' provided -with openings 56 through which heatinggases are admitted to the chamber 2, and which serve to distribute theheating gases uniformly throughout the cross-section of the heatingchamber. Y

The furnace chamber 52 may contain any sort of objects to be heated. Byway of illustration, I have shown an arrangement for lheating liquid,consisting of vertical tubes 57 communicating at their upper and lower95 ends with headers 58 throughl which the liquid to be heated isbrought tov and removed from the tubes 57 by any suitable circulatingmeans, not shown.

For the purpose of reciprocating hot gases through the furnace chamber52, I provide a piston 60 reciprocating vertically in a chamber 61formed by vcircularly curved walls 62. The piston 60 and its attachmentsmay be similar in construction tothose described and claimed in mycopending application for Letters Patent filed December 11, 1922, SerialNo. 606,037. As best shown on Fig. 7 the piston consists of two curveddiscs 63 of metal with a ring 63u between 11,0 them. These discs may becovered by heatinsulating material, as shown at 64. The piston issuspended from a hollow rod 64a which extends through an opening 65 inthe top of the piston chamber and through a ,115 gland 66. The spacewithin the piston is divided into two chambers by means of a horizontalplate 67 having openings 68 near its outer edge. Cooling fluid issupplied to the piston through a tube 69, the lower end of whichvco-mmunicates through an opening 7 0 in the horizontal plate 67 withthe lower chamber of the piston,'and which is connected at its upper endby means of a coupling 71 to a source 12 of water or other coolingmedium. The cooling fluid passes from the lower chamber of the piston'into the upper chamber through the openings 68, and thence passesupwardly through the space 72 between the 130 tube 69 and the inner wallof the piston rod 64a. A coupling 73 is attached to the upper end of thepiston rod 64 for conveying the cooling fluid away from the piston.

The piston and its cooling attachments just described are pivotallysuspended from a link which is itself pivotally suspended from the outerend of a rocking lever 76 that is mounted on a fixed pivot 77 and isconnected by means of a link 78 to a crank 79 on a shaft 80. The shaft80 is mounted in a bearing 81 and is driven, through a set of reduct-iongearing 82 and a suitable coupling 83, from an electric motor 84.

The piston chamber 61 communicates with the furnace chamber throughupper and lower fiues indicated at 85 and 86, respectively. The lowersurface 87 of the flue 85 slopes downwardly and communicates with alateral flue 88, the lowersurface of which also slopes downwardly to theline 89 where it joins the licor of the furnace chamber. Similarly, theupper surface 90 of the lower flue 86 slopes upwardly and communicateswith a lateral flue 91, the upper surface of which also slopes upwardlyto the roof of the furnace chamber. By this arrangement of flues, thehot gases from the piston chamber are distributed in substantially equalamounts over the cross section of the furnace chamber, this distributionbeing made still more uniform by the perforated walls 54with theopenings 56, as described above.

Heat is supplied to ythe piston chamber shown in Figs. 6 and 7 from asingle source of heat represented by a burner which discharges its flameinto a lire-box 96 communicating through! a port 97 with a verticalby-pass flue 98 which communicates with the upper and lower ends ofthepiston chamber 61 through ports 99 and 100, respectively.

Since fresh hot gases are continuously supplied to the system from theburner 95, it is necessary to withdraw continuously correspondingvolumes of waste gases. For this purpose an outlet port 101 is providedin the lower part of the heating chamber 52 midway between its ends andon the side of the heating chamber away from the piston.

The outlet port 101 is connected by means of a vertically elongated pipe102 with a chimney 103. Since the outlet por; 101 is located at thecenter of the heating chamber the gases discharged through it have givenup the greater part of their available heat, because they have been incontact with onehalf of the. objects to be heated. The release of wastegases at this central point is preferred in case the temperature of thecirculated and released gases is relatively low. If thistemperature ishigher it would be preferable to release the gases only after they havepassed over all the bodies to be heated of the piston 60, so as todischarge waste gases through the opening 104 while heating gases areentering at the right end of the chamber 52, Fig. 6, and to dischargethe waste gases through the opening 105 while heating gases are enteringat the left end of the heating chamber. Mechanism for operating suchdampers is shown in my prior application, Serial No. 606,037, filedDecember 11, 1922.

When the piston 60 moves upwardly it forces hot gases through the flues85 and 88 into the chamber 55, at the left of Fig. 6, and thence throughthe openings 56 into the heating chamber 52. A similar volume of gasesis drawn-out of the right end of the heating chamber and through thelues 91 and 86 into the piston chamber 61 below the piston 60. At thesame time a portion of the gases above the piston moves through theby-pass flue 98 into the space below the piston. Fresh hot gases fromthe fire-box 96 are supplied into the by-pass flue 98 and enter thespace below the piston 60 along with the gases traversing the by-passflue. These mixed gases, on issuing into the piston chamber through theport 100, mingle with the gases which enter the piston chamber throughthe flue 86. When the piston 60 descends the same operation takes placein the reverse direction, the main body of hot gases being forced intothe right end of the heating chamber through the flues 86 and 91, and asimilar volume of'gases returning such as the piston 60, and may beconnected to the piston chamber by suitable liues for simultaneousheating. This arrangement is desirable' when the heating chambers arecomparatively small, as in certair types of retorts. t

It will be observed that in the system shown in Figs. 6 and 7, as in thesystem of Figs. 1 to 5, fresh hot gases are introduced fied and theexpense of construction is reduced. An important feature incident toVthis advantage is that the temperature of the hot gasesmoved'alternately from opposite sides to the objects to be heated isabsolutely uniform, since the same source of heat supplies equal heat toeach side of the heating chamber.

The second main advantage of my present system is that the temperatureof the hot gases thrown from two sides against theA bodies to be heatedis thoroughly homogeneous, because no portion of the new heat suppliedat each reciprocation is added to the reciprocating gases while they areon their way 'toward the bodies to be heated, but, on the contrary, thenew heat is added to the reciprocating gases while .they aregoing awayfrom the bodies to be heated and entering the piston chamber. The usedgas coming from the bodies to be heated enters the piston chamber at thesame time as the fresh hot gases from the source of heat, and the twobodies of gases diffuse into each other and mix thoroughly while theyare filling the piston chamber. At the moment of vreversal of thedirection of the piston the inflow of both gases ceases im- -mediately.The mixed gases are then forced out into the heating chamber and theirtemperature becomes even more uniform while they are thus expelled fromthe piston chamber into the heating chamber. Stratification of heat isthereby entirely avoided.

It will be understood that the principles of my invention may be appliedin many ways, and with the 'use of many forms of apparatus other thanthose herein specifically described. Therefore, no limitations are to beimposed on my invention except such as are indicated in the appendedclaims.

I claim as my invention:

l. A method of heating that comprises establishing a reciprocating bodyof fiuid separating a portion of said fluid during each reciprocationthereof, adding heat to said separated portion, and then combining bothportions prior to the next reciprocation.

2. A method of heating that comprises reciprocating hot gases through asystem including a space to be heated, dividing said gases into twostreams during each reciprocation thereof, passing one of said streamsthrough the space to be heated, adding heat to the. other stream andmixing both streams together prior` to thev next lie-1` ciprocati-on.

3. A method of maintaining the tempera;

ture of a body of hot gas while recpirocating saidl gas through a spaceto be heated, that comprises simultaneously reciprocating a second bodyof gas, raising the temperature of said second body, and-mixin the twobodies of gas during each reciprocation thereof. g, .l

4; A method of heating that comprises reciprocating a body of gas incontact with the object or space to be heated, reciprocating anotherbody of gas through another path, raising the temperature ofx the said 1second body Vwhile traversing said path, and

mixing said bodies of gas together prior -to thev next reciprocation.

' 5. Ay method of heating that comprises' reciprocating'a body of gas incontact with .the object or space to be heated, causing a 'portion ofsaid gas to traverse a'by-pass.

communicating at its ends with a path of movement of said heating gas,and adding comprises movement of said firstmamed vbody of gas,

adding hot gases to the gas in said by-pass at a point where thepressure. is neutral, and releasing waste gases from the system atanother point where the pressure is neutral.

8. A method of heating that comprises reciprocating a stream of gasesgincontact with the object or space'to'beheated, addingwfresh hot gases toone side o f the stream, allowing a corresponding volume of thesurplus-gases to spread from this side across the width of saidstreamand finally removing the waste gases from the other sideof saidstream.

9. A method of heating an elongated chamber or object that comprisesreciproeating gases in contact with its full length, adding new hotgases to said reciprocatin gasesat one portion only of the length o saidchamber or object, and removing waste gases from vanother portion ofsaid gases.

10. A method of heating and guiding gases which are reciprocated incontact with the object or space to be heated, that -comprises adding`heat to a portion only of said reciprocated gases, allowing gases fromsaid heated portion to spread into another portion of said reciprocatedgases, and removing waste gases from the latter portion of saidreciprocated gases.

11. The method which comprises reciprocating a body of hot gases incontact with an object to be heated, and supplying new hot gases theretofrom a single source of heat, alternately at opposite sides of saidobject, simultaneously with decrease of pressure at said points byreason of said reciprocation.

12. The method which comprises reciprocating a body7 of heating gasesthrough a chamber by effecting variations in gas pressure, andintroducing additional hot gases to said chamber at a point ofrelatively low pressure.

13. The method which comprises reciprocating a body of heating gasesthrough a chamber by effecting variations in gas pressure at oppositesides of said chamber, and introducing additional hot gases to saidchamber at points of relatively low pressure adjacent to said sides.- f

14. The combination with a chamber to be heated, of means forreciprocating heating gases through said chamber, and means forreplenishing the gases with added hot gases from a single source ofsupply, alternately to each of opposite sides ofy said chamber duringperiods when said heating gases are moving toward the respective sides.

15. The combination with afurnace having a space to be heated, of meansfor reciprocating gases'therethrough, centrally located means for addinghot gases to the reciprocated gases, and means for alternatelyy feedingthe added hot gases into the reciprocated gases at points where thelast-named gases are under a reduced pressure;

16. In a furnace, a heating chamber, an auxiliary chamber adjacent theheating chamber, lues connecting the ends of the heating chamber withthe ends of the auxiliary chamber, a combustion chamber having feedingchannels for supplying hot gases into the connecting flues, and means inthe auxiliary chamber for causing movement of gases back' anl forththrough the heating chamber and for directing the sup- 'ply of fresh hotgases into the moved gases as they emerge from the heating chamber.

17. In a furnace," a heating chamber adapted to receive heating gases,gas storage chambers for the gases at opposite sides thereof. fluesconnecting the heating chamber with the storage chambers, meanscommunicating with both lues, for generating new hot gases, and meansfor simultaneously effecting reciprocation of the heating gases throughthe Vheating chamber and the inliux of new hot gases into the heatinggases whenthe last-named Oases are passing through the connecting ues.

18. Heating apparatus comprising a main chamber adapted to receiveheating gases, an auxiliary chamber, means for alternately increasingand decreasing the pressure in the auxiliary chamber, for effectingmovement of the heating gases through the main chamber, and means foreffecting an inux of new hot gases into the auxiliary chamber whendecreased pressure exists therein.

19. Heating apparatus comprising an enclosure to be heated, means forreciprocating fluid through said enclosure, means for separating aportion of said Huid during each reciprocation thereof, meansfor addingheat to said separated portion, and means for thereafter combining saidportions prior to the next reciprocation.

20. Heating apparatus comprising an enclosure to be heated, means forreciprocating -gases through said enclosure, means for separating aportion of said gases during each reciprocation thereof, a burneradapted to add fresh hot gases to said separated portion, and means forthereafter combining both portions prior to the next reciprocation.

21. Heating apparatus comprising an enclosure to be heated, means for,reciprocating gases through said enclosure, means for dividing saidgases into two streams during each reciprocation thereof, means fordirecting one of said sti cams through the said enenclosure, means foradding heat to the other stream, and means for thereafter mixing saidstreams prior to the next reciprocation.

22. Heating apparatus comprising an enclosure to be heated, means forreciprocating gases through said enclosure, a by-pass channel having itsends connected to the path of said reciprocating gases, and means foradding heat to the gases traversing said by-pass.

23. Heating apparatus comprising an enclosure -to be heated, means forreciprocat-` ing gases through said enclosure, a by-pass channel ofsmaller capacity than the main path of said reciprocating gases andhaving its ends connected to, said path, and means for introducing hotgases into said by-pass.

'the length of said enclosure, and means for removing waste gases fromanother portion of said enclosure.

26. Heating apparatus comprising an elongated enclosuie to be heated,means for reciprocating gases transversely in contact with the fulllength of said enclosure, means for adding hot gases at one end only ofsaid enclosure, and means for removing waste gases from the opposite endof said enclosure.

27. Heating apparatus comprising an enclosure to be heated, a piston forreciprocating gases through said enclosure, and a single source of heatarranged to supply equal amounts of heat to said reciprocating gasesduring each reciproeation thereof.

28. Heating apparatus comprising an elongated heatingv chamber, anelongated. piston chamber, flues connecting said cham-A bers atthe sidesthereof, by-pass channels having their ends opening into said lues, andmeans for adding heat to the gases traversing said by-pass channels.

29. Heating apparatus lcomprising an elongated heating chamber, anelongated piston chamber, flues connecting said chambers at the sidesthereof, by-pass channels having their ends opening into said flues, aflue communicating with saidV by-pass channels, and a burner forintroducinghot gases into said last-named flue.

30.` Heating apparatus comprising an elongated heating chamber, anelongated piston chamber, lues connecting said chambers atthe sidesthereof, by-pass channels disposed at one'part only of said heatingchamber and having their ends opening into certain ofy said llues, andmeans for adding heat to the gases traversing said by-pass channels'.

31. Heating apparatus comprising an elongated heating chamber, anelongated piston chamber, flues connecting said chambers at the sidesthereof, by-pass channels disposed at one end only of said heatingchamber and having their ends opening into certain of said lines, a flueextending transversely of said by-pass channels and -communicatingtherewith through openings, and a burner for introducing hot gases intosaid last-named flue.

32. Heating apparatus comprising an elongated heating chamber, anelongated iston chamber` iues connecting said chamgers at the sidesthereof, by-pass channels disposed at one part only of said heatingchamber and having their ends opening into certain of said flues, a flueextending transversely of said by-pass channels and communicatingtherewith through openings, a burner for introducing hot gases into saidlast-named flue, and means for adjusting the effective area of saidopenings.

33. Heating apparatus comprising an piston chamber, lues connecting saidchambers at the sides thereof, by-pass channels disposed between saidchambers and having their ends opening into said ilues, a flue extendingfrom one end of said enclosure and between 7said chambers, a burner-forintroducing hot gases into said last-named flue, and openings forconnecting said lastnamed flue and said by-pass channels.

elongated horizontal heating chamber, an

35. Heating apparatus comprising an l elongated piston chamber adjacentto said heating chamber, flues connecting said chambers at'thesides'thereof, spaced b pass channels having their ends opening intocertain of said vertical lues, said bypass channels -being disposed atone end portion only of said heating chamber, a

horizontal flue extending transversely to said by-pass'channels,openings for connecting said horizontal flue and said :by-pass channels,a burner at the outer end of saidI horizontal flue, and an outlet forwaste gases at the end of said heat-ing chamber opposite to said burner.v

36. Heating apparatus comprising an elongated horizontal heatingchamber, an elongated piston chamber adjacent to said heating chamber,vertical lues connecting said chambers at the sides thereof, transversepartition means for dividing said piston chamber into sections,v pistonsections disposed in the sections of said piston chamber and adapted tooscillate on a common horizontal axis extending lengthwise of saidchambers, spaced by-pass channels having their ends opening into certainof said vertical lues, said by-pass channels being disposed between saidchambers and at one end only of said heating chamber, a horizontal Hueextending between said chambers and transversely to said b v-passchannels, openings for connecting said horizontalY flue and said by-passchannels, a burner at the outer end of said horizontal flue, and anoutlet for waste gases at the end of said heating chamber xopposite tosaid burner.

37. In heating apparatus, the combination with an oscillatory piston, ofa cirv cularly curved wall of refractory material beneath said pistonand a circularly curved metal wall supporting said refractory wall.

38. ln heating apparatus, the combination with an oscillatory piston, ofa wall ofv refractory material curved circularly through an arc 4of lessthan 360, means disposed at the opposite ends of said wall for securingthe ends' of said wall in position, and metal members connecting thesaid securing means, the said members surrounding the outer surface ofsaid refractory wall and holding said wall in position.

39. ln' heating apparatus, the combination withan oscillatory piston, ofa wall of refractory material curved circularly through an arc of lessthan 360, means disposed at -the opposite ends o f said wall forsecuring the ends of said wall in position, and metal members connectingthe said securing means, the said members surrounding the outer surfaceof said refractory wall and holding said wall in position, andStructural means for positioning said securing means.

40. ln heating apparatus, the combination of a heating chamber, a pistonchamber, a swinging piston in said piston chamber, a partition wallbetween said heating chamber and said piston chamber, a circularly.curved wall beneath said piston chamber, a circularly curved plate forsupporting said circularly curved wall, structural means for securingthe ends of said partition wall in position, and structural means foruniting said plate tural securing means together.

41. lln heat-ing apparatus, the combination of aheating chamber, apiston chamber, a swinging piston in said piston chamber, a partitionwall -between said heating chamber and said piston chamber, a circularlycurved wall beneath said piston chamber, a circularly curved plate forsupporting said circularlymurved wall, structural means 4for securingthe ends of said partition Wall in position, and structural means 'forunitingsaid plate and said struc- -tural Lsecuring means together, saidlastnamed means being also adapted to support the'weight of saidchambers. lin testimony whereof I the said lFRANZ PUENING have hereuntoVset my hand.

' FRANZ PUENING.

and said struc-I.

